Concrete dam



D C. HENNY CONCRETE DAM March 21, 1933.

Filed Sept. 21, 1932 2 Sheets-Sheet 1 March 1933- D. c. HENNY 1,902,

CONCRETE DAM Filed Sept. 21, 1952 2 Sheets-Sheet 2 Patented Mar. 21, 1933 UNITED STATES DAVID OHRISTIAAN HENNY, or PORTLAND, OREGON concnnrn DAM Application filed September 21, 1932. Serial No. 684,098;

My invention relates to concrete dams in which serrated contraction joints are introduced at the desired places.

The objects of my invention are to render innocuous the detrimental efiects of contraction and expansion in concrete dams; to restrict the unavoidable effects of contraction and expansion as much as possible to definite and predetermined planes; to stop the formation of shrinkage cracks; to prevent the failure of dams as caused by the haphazard formation of a certain kind of shrinkage cracks; and to give the contraction joints a form which utilizes the full crosssectional surface of the concrete in compression.

Other objects and advantages are to be found in the construction and arrangement of parts, as will be described in the specification, and particularly pointed out in the appended claims.

I attain these objects with the mechanism illustrated in the accompanying drawings, in which:

Fig. l is a vertical cross-section of a gravity dam or a gravity arch dam.

Fig. 2 is a cross-sectional elevation of a buttress-supported dam.

Fig. 3 is a detail of the contraction joint.

Fig. i is a plan view of the arch dam.

Similar numerals refer to similar parts throughout the several views.

In structures as exemplified by Fig. 1, the principal direction of stresses is as indicated by the arrow 1. It is obvious that a shrinkage crack-especially one that is more or less straight and flatin the direction of the arrow 2 would aifect the equilibrium of a dam very materially, and by permitting the two concrete surfaces of the crack to slide upon each other lead to a failure of the dam. To overcome any danger threatening from this source, I introduce a serrated contraction joint whose general plane and direction conform to the one indicated by the arrow 2. As particularly illustrated in Fig. 3, those contact surfaces 3 which are under compression are held normal to the direction of principal stresses 1, while the immediately adjoining contacting surfaces 4 run parallel to the direction of principal stress 1, and are consequently located in a plane of no shear.

.of a large mass of concrete prevents the development of a dangerous shrinkage cracks '60 at intermediate points. V

In Fig. 2 the direction of the serrated contact planes is alsoalternately normal and parallel tothe direction of principal stresses 5 in the buttress 6 where the general plane of the contraction joint is indicated by the arrow 7 V 1.

In Fig. 4, which refers toarch dams, the principal arch stress would not be directed more or less vertically toward the base, as shown in Figs. 1 and 2, but, rather, more or less horizontally toward the abutments as indicated by the arrow 8. In such dams, contraction joints are usually made radial. It may be desirable, for important constructional reasons, for one or more of such joints in an arch dam to deviate from the radial direction as indicated by the arrow 9. A joint thus deviating if made substantially fiat or even if provided with usual interlocking keys, will be essentially weak for the purpose of resisting shear and for transmitting arch compression stresses. By introducing in such joints serrations substantially vertical, I and having planes alternately substantially normal and parallel to the principal stress, as referred to in the description of Figs- 1 and 2, I attain a joint which is, in all respects, as strong as a radial joint. I

Only one contraction joint is shown in each type of dam toillustrate the principle of my invention. It is, of course, obvious that a plurality of joints must be employed where the magnitude or nature of the dam demands it.

.Having thus described my invention, it will be seen that my objects have been accomplished, and though I have showed the preferred form of construction, I reserve to myself the right to make minor changes providing I do not contravene the spirit and principle of my invention.

I claim:

1. In a concrete dam serrated contraction joints extending in a substantially vertical 7 plane with the contacting surfaces thereof being alternately substantially normal and parallel to the direction of principal stresses.

2. In a concrete dam of the arch type serrated contraction joints extending in a substantially vertical plane deviating from a radial direction with the contacting surfaces thereof being alternately substantially normal and parallel to the direction of arch stresses.

3. In a concrete dam of the gravity or combined gravity and arch type serrated con- 1 traction jointsextending in a substantially vertical-plane with the contacting surfaces thereof being substantially normal and parallel to the direction of principal stresses in an up and down-stream direction.

In testimony whereof I affix my signature.

1). c; HENNY. 

